This project will be concerned with carnitine biosynthesis and its regulation in the rat. Trimethyllysine hydroxylase of the mitochondria and gamma-butyrobetaine aldehyde dehydrogenase of the cytoplasm will be further purified and characterized. The activity of these enzymes, as well as serine transhydroxymethylase, which functions between these two will be studied in various perfused organs with the objective of attaining a thorough understanding of carnitine synthesis transport and function. The individual intermediates will be used as labeled substrates to determine the degree of involvement of each organ in the various biosynthetic steps. Efforts will be made to design and prepare antagonists of carnitine or one of its precursors, which will lead to the depletion or interference with function of carnitine, so that the effects of a deficiency can be studied in the whole animal or specific organs of the rat. Efforts will then be made to relate the various reports of human carnitine deficiency to the observations in experimental animals.